Genetic analysis of Bromus tectorum in the eastern and western Mediterranean regions

Genetic diversity within and among 42 native populations of Bromus tectorum (cheatgrass) was characterized within two regions, the eastern Mediterranean and the western Mediterranean. Two hypotheses  were tested for the genetic diversity of these populations: 1) populations from the eastern Mediterranean are more genetically diverse compared with populations to the west, a potential consequence of the species’ westward dispersal with the spread of agriculture and 2) populations across the Mediterranean contain comparable genetic diversity but display high genetic differentiation, a potential consequence of both regions having served as refugia during glacial advances in the late Quaternary Period.  Populations in the eastern Mediterranean possess 16 polymorphic loci and 37 multilocus genotypes.  In contrast, populations from the western Mediterranean include a subset of these polymorphic loci (9) and fewer multilocus genotypes (19), consistent with the dispersal of B. tectorum with the ...

本研究对东地中海与西地中海两个区域内的42个旱雀麦（Bromus tectorum，cheatgrass）本土种群的种内及种群间遗传多样性进行了表征分析。针对这些种群的遗传多样性，本研究验证了两项假说：其一，东地中海种群的遗传多样性高于西部种群，该现象可能源于该物种随农业扩张向西扩散的历史过程；其二，整个地中海区域的种群遗传多样性水平相当，但种群间遗传分化程度较高，这一结果可能是晚第四纪冰期推进时，东西地中海均作为物种避难所所致。东地中海种群共检测到16个多态性位点（polymorphic loci）与37个多位点基因型（multilocus genotypes）。与之相比，西地中海种群仅包含其中9个多态性位点，且多位点基因型数量更少（19个），这与旱雀麦随[...]扩散的研究结果一致。